The present invention relates to spectral Doppler ultrasound. Spectral Doppler ultrasound imaging provides an image of velocities (vertical axis) values modulated by energy as a function of time (horizontal axis). This spectrum may be used for studying fluid flow or tissue motion within a patient. By transmitting a plurality of pulses at a single gate location, a spectral Doppler response is generated in response to received echo signals. The frequency spectrum of the object's motion or flow for a single spatial region is estimated and displayed as a function of time. Flow or tissue deformation parameters can be derived from the acquisition.
Sonographers manually adjust the gate location, gate size, transmit frequency and other spectral Doppler imaging control parameters in order to acquire a desirable image. The gate placement is assisted by display of a 2D B-mode image of the anatomy of interest. Some processes have been proposed for automatic placement of the spectral Doppler gate.
Spectral Doppler ultrasound imaging provides frequency information for a location, so may not provide spatial information. Spectral information may be provided for different depths along a same scan line. Spectral information for other locations or scan lines is acquired sequentially. In a routine scan, the user often places a series of single-gates to optimize the spectrum, and the process is repeated for each location in the same image plane (e.g. mitral valve and mitral annulus). Certain cardiac measurements require evaluating the ratios of peak flow velocity and tissue displacement. In the case of vascular application, multiple gates are placed pre- and post-stenosis to perform clinically relevant assessment. In other scenarios, distinct regions of interest on cardiac walls may need to be studied in relation to each other to evaluate desynchrony in a heart ventricle.
Spatial flow may be represented by color or flow Doppler imaging. The mean Doppler frequency shift or mean velocity for each of a plurality of spatial locations along multiple scan lines is acquired. The mean velocities are mapped to colors. However, mean velocity, such as derived from the change in frequency for Doppler processing, may not provide sufficient information regarding motion.